BONE CONDUCTION

[Michael Gorga]

Although it is often assumed that there is 0 dB interaural attenuation by bone 
conduction, this is technically not true.  If one moves the bone vibrator used 
for clinical audiometric measurements from the mastoid to the forehead, for
example, there is a loss of as much as 15 dB, depending on frequency.  The ANSI
standards for bone conduction reflect these differences in the reference
equivalent force levels for mastoid versus forehead placement.  If one can
assume that the transducer used with bone conduction hearing aids perform
similarly, then one might anticipate a similar attenuative effect if the
vibrator is moved off of the mastoid.  

Michael Gorga
Name:		Michael P. Gorga
Address:	BTNRH
		555 North 30th Street
		Omaha, NE   68131
Telephone:	402/498-6604
FAX:		402/498-6638
e-mail:		gorga at boystown.org